1. Field
The invention relates to improved teat cup assemblies in vacuum operated, automatic milking machines.
2. State of the Art
Conventional automatic milking machines utilize teat cup assemblies including a hollow, rigid outer shell or cup having a port which is adapted to be attached to a pulsating vacuum line, and a resilient, tubular liner or inflation extending longitudinally of the shell or cup. The ends of the inflation make sealing engagement with the shell to form an annular vacuum chamber between the shell and the inflation. The pressure in the annular chamber is alternated between subatmospheric pressure and a higher pressure, typically atmospheric, by the pulsating vacuum line attached to the shell. A constant vacuum line is connected to the lower end of the inflation to draw milk from the cow's teat which is received in the upper end of the inflation. The interior of the inflation is, thus, maintained at a constant subatmospheric pressure, and the alternating pressure in the annular chamber periodically forces the walls of the inflation inwardly resulting in a massaging action on the teat as well as collapsing the walls of the inflation below the teat which periodically relieves the teat from exposure to the vacuum in the constant vacuum line.
It is important that the upper portion of the inflation grips the teat firmly to prevent vacuum loss and disengagement of the teat cup from the teat, as well as to prevent the teat cups from moving higher up on the teats during the pulsations of the milking machine, which can ultimately result in constriction of the teat and premature shut off of milk from the udder even though the udder is only partially emptied. The teats of different cows vary considerably in their diameter and length. Changes in teat sizes also occur during the milking. These variations and changes make it very difficult to produce teat cups which can be used in milking a number of cows. In my prior U.S. Pat. No. 3,308,788 there is disclosed a teat cup assembly in which a resilient disk element is mounted on top of the teat cup in position to engage the cow's teat and resiliently retain the cup from falling off the teat. Unfortunately, the teat cup assembly was relatively expensive both to manufacture and to maintain because of the number of individual components in the assembly. In other of my prior art patents, i.e., U.S. Pat. Nos. 3,659,557 and 3,096,740, teat cup assemblies are provided in which the inflation is molded so as to incorporate a diaphgagm and an elastic means, respectively, integrally therein. Other inflations which are molded so as to incorporate a resilient retaining element integrally therein as disclosed in U.S. Pat. Nos. 2,744,496; 3,771,494; and 3,873,521.
Objectives
A principal objective of the present invention is to provide an improvement in teat cup assemblies utilizing an inflation and teat engaging diaphragm made of resilient, elastomeric material, wherein a protective cap member is provided for securing the diaphragm portion to the assembly. A particular objective is to provide a teat cup assembly utilizing a molded diaphragm member having a central opening therein and an extruded, tubular inflation, wherein the opening in the diaphragm has a smaller circumference than the cross-sectional circumference of the tubular inflation. Another objective is to provide a teat cup assembly in which the inflation and diaphragm are made of silicone rubber which is not subject to deterioration due to soil, fat, ozone, etc., and which has been found to have a much greater life than assemblies made with molded rubber inflations. A further objective is to provide an inflation having a novel mouth portion which maintains sufficient contact with the teat of the cow so as to prevent the teat cup from dropping off the teat, but still sufficiently flexible to be used on teats of various sizes to improve milking efficiency and reduce tissue damage and mastitis.